The experiment on quasi-phase-matched second harmonic generation (SHG) in a channel waveguide was reported.The waveguide was made by annealed proton exchange in the periodically poled lithium niobate (PPLN) with the period of PPLN of 14.9 μm, which was designed for cascading wavelength conversion in dense wavelength division multiplexer optical communications.The measurement results of SHG conversion efficiency as a function of fundamental wavelength at room temperature fit well to sinc2 shape.The peak of SHG conversion efficiency was 75％ · W-1 · cm-2 as well as reported. The relationship between the center fundamental wavelength and tempera ture shows that SHG can be effectively tuned by the temperature in PPLN waveguide.